diff --git a/src/utils/command-helpers.ts b/src/utils/command-helpers.ts
index 6397cddaf86..701768ae614 100644
--- a/src/utils/command-helpers.ts
+++ b/src/utils/command-helpers.ts
@@ -102,8 +102,7 @@ export const pollForToken = async ({
     }
     return accessToken
   } catch (error_) {
-    // @ts-expect-error TS(2571) FIXME: Object is of type 'unknown'.
-    if (error_.name === 'TimeoutError') {
+    if (error_ instanceof Error && error_.name === 'TimeoutError') {
       return logAndThrowError(
         `Timed out waiting for authorization. If you do not have a ${chalk.bold.greenBright(
           'Netlify',
diff --git a/src/utils/dev.ts b/src/utils/dev.ts
index 8f929be9270..12b30ce0f47 100644
--- a/src/utils/dev.ts
+++ b/src/utils/dev.ts
@@ -41,8 +41,7 @@ const ENV_VAR_SOURCES = {
 const ERROR_CALL_TO_ACTION =
   "Double-check your login status with 'netlify status' or contact support with details of your error."
 
-// @ts-expect-error TS(7031) FIXME: Binding element 'site' implicitly has an 'any' typ... Remove this comment to see the full error message
-const validateSiteInfo = ({ site, siteInfo }) => {
+const validateSiteInfo = ({ site, siteInfo }: { site: { id?: string }; siteInfo: SiteInfo }) => {
   if (isEmpty(siteInfo)) {
     return logAndThrowError(
       `Failed to retrieve project information for project ${chalk.yellow(site.id)}. ${ERROR_CALL_TO_ACTION}`,
@@ -78,10 +77,13 @@ const getAccounts = async ({ api }: { api: NetlifyAPI }) => {
   }
 }
 
-// @ts-expect-error TS(7031) FIXME: Binding element 'api' implicitly has an 'any' type... Remove this comment to see the full error message
-const getAddons = async ({ api, site }) => {
+const getAddons = async ({ api, site }: { api: NetlifyAPI; site: { id?: string } }) => {
+  const { id } = site
+  if (!id) {
+    return []
+  }
   try {
-    const addons = await api.listServiceInstancesForSite({ siteId: site.id })
+    const addons = await api.listServiceInstancesForSite({ siteId: id })
     return addons
   } catch (error_) {
     return logAndThrowError(
@@ -92,21 +94,21 @@ const getAddons = async ({ api, site }) => {
   }
 }
 
-// @ts-expect-error TS(7031) FIXME: Binding element 'addons' implicitly has an 'any' t... Remove this comment to see the full error message
-const getAddonsInformation = ({ addons, siteInfo }) => {
+type Addon = Awaited<ReturnType<NetlifyAPI['listServiceInstancesForSite']>>[number]
+
+const getAddonsInformation = ({ addons, siteInfo }: { addons: Addon[]; siteInfo: SiteInfo }) => {
   const urls = Object.fromEntries(
-    // @ts-expect-error TS(7006) FIXME: Parameter 'addon' implicitly has an 'any' type.
     addons.map((addon) => [addon.service_slug, `${siteInfo.ssl_url}${addon.service_path}`]),
   )
-  // @ts-expect-error TS(7006) FIXME: Parameter 'addon' implicitly has an 'any' type.
   const env = Object.assign({}, ...addons.map((addon) => addon.env))
   return { urls, env }
 }
 
 const getSiteAccount = ({ accounts, siteInfo }: { accounts: Account[]; siteInfo: SiteInfo }): Account | undefined => {
-  const siteAccount = accounts.find((account) => account.slug === siteInfo.account_slug)
+  const { account_id: accountId, account_slug: accountSlug } = siteInfo
+  const siteAccount = accounts.find((account) => account.slug === accountSlug || account.id === accountId)
   if (!siteAccount) {
-    warn(`Could not find account for project '${siteInfo.name}' with account slug '${siteInfo.account_slug}'`)
+    warn(`Could not find account for project '${siteInfo.name}' with account slug '${accountSlug}'`)
     return undefined
   }
   return siteAccount
@@ -155,7 +157,7 @@ export const getSiteInformation = async ({
     return {
       addonsUrls,
       siteUrl: siteInfo.ssl_url,
-      accountId: account?.id,
+      accountId: account?.id ?? siteInfo.account_id,
       capabilities: {
         backgroundFunctions: supportsBackgroundFunctions(account),
         aiGatewayDisabled: siteInfo.capabilities?.ai_gateway_disabled ?? false,
@@ -181,10 +183,11 @@ export const getSiteInformation = async ({
   }
 }
 
-// @ts-expect-error TS(7006) FIXME: Parameter 'source' implicitly has an 'any' type.
-const getEnvSourceName = (source) => {
-  // @ts-expect-error TS(7053) FIXME: Element implicitly has an 'any' type because expre... Remove this comment to see the full error message
-  const { name = source, printFn = chalk.green } = ENV_VAR_SOURCES[source] || {}
+const getEnvSourceName = (source: string) => {
+  const sourceConfig = (
+    ENV_VAR_SOURCES as Record<string, { name: string; printFn: (s: string) => string } | undefined>
+  )[source]
+  const { name = source, printFn = chalk.green } = sourceConfig || {}
 
   return printFn(name)
 }
@@ -192,10 +195,18 @@ const getEnvSourceName = (source) => {
 /**
  * @param {{devConfig: any, env: Record<string, { sources: string[], value: string}>, site: any}} param0
  */
-// @ts-expect-error TS(7031) FIXME: Binding element 'devConfig' implicitly has an 'any... Remove this comment to see the full error message
-export const getDotEnvVariables = async ({ devConfig, env, site }): Promise<EnvironmentVariables> => {
-  const dotEnvFiles = await loadDotEnvFiles({ envFiles: devConfig.envFiles, projectDir: site.root })
-  // @ts-expect-error TS(2339) FIXME: Property 'env' does not exist on type '{ warning: ... Remove this comment to see the full error message
+export const getDotEnvVariables = async ({
+  devConfig,
+  env,
+  site,
+}: {
+  devConfig: { envFiles?: string[]; env_files?: string[]; [key: string]: unknown }
+  env: EnvironmentVariables
+  site: { root?: string; [key: string]: unknown }
+}): Promise<EnvironmentVariables> => {
+  const envFiles = devConfig.envFiles || devConfig.env_files
+  // eslint-disable-next-line no-restricted-properties
+  const dotEnvFiles = await loadDotEnvFiles({ envFiles, projectDir: site.root || process.cwd() })
   dotEnvFiles.forEach(({ env: fileEnv, file }) => {
     const newSourceName = `${file} file`
 
@@ -272,11 +283,17 @@ export const acquirePort = async ({
   return acquiredPort
 }
 
-// @ts-expect-error TS(7006) FIXME: Parameter 'fn' implicitly has an 'any' type.
-export const processOnExit = (fn) => {
+export const processOnExit = (fn: (codeOrSignal: string | number) => void | Promise<void>) => {
   const signals = ['SIGINT', 'SIGTERM', 'SIGQUIT', 'SIGHUP', 'exit']
   signals.forEach((signal) => {
-    process.on(signal, fn)
+    process.on(signal, (codeOrSignal) => {
+      const result = fn(codeOrSignal)
+      if (result instanceof Promise) {
+        result.catch(() => {
+          // ignore
+        })
+      }
+    })
   })
 }
 
diff --git a/src/utils/dot-env.ts b/src/utils/dot-env.ts
index 27cebc92163..c8f2de88845 100644
--- a/src/utils/dot-env.ts
+++ b/src/utils/dot-env.ts
@@ -7,28 +7,46 @@ import { isFileAsync } from '../lib/fs.js'
 
 import { warn } from './command-helpers.js'
 
-// @ts-expect-error TS(7031) FIXME: Binding element 'envFiles' implicitly has an 'any'... Remove this comment to see the full error message
-export const loadDotEnvFiles = async function ({ envFiles, projectDir }) {
+export type DotEnvFileResult = {
+  file: string
+  env: Record<string, string>
+}
+
+export type DotEnvWarningResult = {
+  warning: string
+}
+
+export type DotEnvResult = DotEnvFileResult | DotEnvWarningResult
+
+export const loadDotEnvFiles = async function ({
+  envFiles,
+  projectDir,
+}: {
+  envFiles?: string[]
+  projectDir: string
+}): Promise<DotEnvFileResult[]> {
   const response = await tryLoadDotEnvFiles({ projectDir, dotenvFiles: envFiles })
 
-  // @ts-expect-error TS(2532) FIXME: Object is possibly 'undefined'.
-  const filesWithWarning = response.filter((el) => el.warning)
+  const filesWithWarning = response.filter((el): el is DotEnvWarningResult => 'warning' in el)
   filesWithWarning.forEach((el) => {
-    // @ts-expect-error TS(2532) FIXME: Object is possibly 'undefined'.
     warn(el.warning)
   })
 
-  // @ts-expect-error TS(2532) FIXME: Object is possibly 'undefined'.
-  return response.filter((el) => el.file && el.env)
+  return response.filter((el): el is DotEnvFileResult => 'file' in el && 'env' in el)
 }
 
 // in the user configuration, the order is highest to lowest
 const defaultEnvFiles = ['.env.development.local', '.env.local', '.env.development', '.env']
 
-// @ts-expect-error TS(7031) FIXME: Binding element 'projectDir' implicitly has an 'an... Remove this comment to see the full error message
-export const tryLoadDotEnvFiles = async ({ dotenvFiles = defaultEnvFiles, projectDir }) => {
+export const tryLoadDotEnvFiles = async ({
+  dotenvFiles = defaultEnvFiles,
+  projectDir,
+}: {
+  dotenvFiles?: string[]
+  projectDir: string
+}): Promise<DotEnvResult[]> => {
   const results = await Promise.all(
-    dotenvFiles.map(async (file) => {
+    dotenvFiles.map(async (file): Promise<DotEnvResult | undefined> => {
       const filepath = path.resolve(projectDir, file)
       try {
         const isFile = await isFileAsync(filepath)
@@ -37,8 +55,9 @@ export const tryLoadDotEnvFiles = async ({ dotenvFiles = defaultEnvFiles, projec
         }
       } catch (error) {
         return {
-          // @ts-expect-error TS(2571) FIXME: Object is of type 'unknown'.
-          warning: `Failed reading env variables from file: ${filepath}: ${error.message}`,
+          warning: `Failed reading env variables from file: ${filepath}: ${
+            error instanceof Error ? error.message : String(error)
+          }`,
         }
       }
       const content = await readFile(filepath, 'utf-8')
@@ -48,5 +67,5 @@ export const tryLoadDotEnvFiles = async ({ dotenvFiles = defaultEnvFiles, projec
   )
 
   // we return in order of lowest to highest priority
-  return results.filter(Boolean).reverse()
+  return results.filter((result): result is DotEnvResult => Boolean(result)).reverse()
 }
diff --git a/src/utils/telemetry/report-error.ts b/src/utils/telemetry/report-error.ts
index 81fc774de4f..e3fb543c0ab 100644
--- a/src/utils/telemetry/report-error.ts
+++ b/src/utils/telemetry/report-error.ts
@@ -2,7 +2,9 @@ import os from 'os'
 import { dirname, join } from 'path'
 import process, { version as nodejsVersion } from 'process'
 import { fileURLToPath } from 'url'
+import { inspect } from 'util'
 
+import { type Event } from '@bugsnag/js'
 import { getGlobalConfigStore } from '@netlify/dev-utils'
 import { isCI } from 'ci-info'
 
@@ -12,44 +14,75 @@ import { cliVersion } from './utils.js'
 
 const dirPath = dirname(fileURLToPath(import.meta.url))
 
+interface ReportErrorConfig {
+  severity?: Event['severity']
+  metadata?: Record<string, Record<string, unknown>>
+}
+
 /**
- *
- * @param {import('@bugsnag/js').NotifiableError} error
- * @param {object} config
- * @param {import('@bugsnag/js').Event['severity']} config.severity
- * @param {Record<string, Record<string, any>>} [config.metadata]
- * @returns {Promise<void>}
+ * Report an error to telemetry
  */
-// @ts-expect-error TS(7006) FIXME: Parameter 'error' implicitly has an 'any' type.
-export const reportError = async function (error, config = {}) {
+export const reportError = async function (error: unknown, config: ReportErrorConfig = {}): Promise<void> {
   if (isCI) {
     return
   }
 
   // convert a NotifiableError to an error class
-  const err = error instanceof Error ? error : typeof error === 'string' ? new Error(error) : error
+  let err: Error
+  if (error instanceof Error) {
+    err = error
+  } else if (typeof error === 'string') {
+    err = new Error(error)
+  } else if (typeof error === 'object' && error !== null && ('message' in error || 'name' in error)) {
+    const errorObject = error as Record<string, unknown>
+    const message = typeof errorObject.message === 'string' ? errorObject.message : 'Unknown error'
+    err = new Error(message)
+    if (typeof errorObject.name === 'string') {
+      err.name = errorObject.name
+    }
+    if (typeof errorObject.stack === 'string') {
+      err.stack = errorObject.stack
+    }
+  } else {
+    err = new Error(typeof error === 'object' && error !== null ? inspect(error) : String(error))
+  }
 
   const globalConfig = await getGlobalConfigStore()
 
-  const options = JSON.stringify({
-    type: 'error',
-    data: {
-      message: err.message,
-      name: err.name,
-      stack: err.stack,
-      cause: err.cause,
-      // @ts-expect-error TS(2339) FIXME: Property 'severity' does not exist on type '{}'.
-      severity: config.severity,
-      user: {
-        id: globalConfig.get('userId'),
+  let options: string
+  try {
+    options = JSON.stringify({
+      type: 'error',
+      data: {
+        message: err.message,
+        name: err.name,
+        stack: err.stack,
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        cause: (err as any).cause ? inspect((err as any).cause) : undefined,
+        severity: config.severity,
+        user: {
+          id: globalConfig.get('userId'),
+        },
+        metadata: config.metadata ? inspect(config.metadata) : undefined,
+        osName: `${os.platform()}-${os.arch()}`,
+        cliVersion,
+        nodejsVersion,
       },
-      // @ts-expect-error TS(2339) FIXME: Property 'metadata' does not exist on type '{}'.
-      metadata: config.metadata,
-      osName: `${os.platform()}-${os.arch()}`,
-      cliVersion,
-      nodejsVersion,
-    },
-  })
+    })
+  } catch {
+    // If stringify fails, we at least try to report a simplified error
+    options = JSON.stringify({
+      type: 'error',
+      data: {
+        message: `Error reporting failed: ${err.message}`,
+        name: 'ErrorReportingError',
+        severity: config.severity,
+        osName: `${os.platform()}-${os.arch()}`,
+        cliVersion,
+        nodejsVersion,
+      },
+    })
+  }
 
   // spawn detached child process to handle send and wait for the http request to finish
   // otherwise it can get canceled
diff --git a/src/utils/types.ts b/src/utils/types.ts
index f2c33e4b541..76aa80304a0 100644
--- a/src/utils/types.ts
+++ b/src/utils/types.ts
@@ -219,7 +219,14 @@ export interface Template {
 }
 
 type EnvironmentVariableScope = 'builds' | 'functions' | 'runtime' | 'post_processing'
-export type EnvironmentVariableSource = 'account' | 'addons' | 'configFile' | 'general' | 'internal' | 'ui'
+export type EnvironmentVariableSource =
+  | 'account'
+  | 'addons'
+  | 'configFile'
+  | 'general'
+  | 'internal'
+  | 'ui'
+  | (string & {})
 
 export type EnvironmentVariables = Record<
   string,