Bump TypeScript from v3.9.7 to v4.5.5

I intended to use 'type' imports & optional-chaining / null coalescing features, so I upgraded TS, but unfortunately, those features can't be used in this repo until tslint is replaced with ESLint

package.json

@@ -132,7 +132,7 @@
     "tslint": "^5.11.0",
     "tslint-config-prettier": "^1.15.0",
     "typedoc": "0.9.0",
-    "typescript": "^3.9.7",
+    "typescript": "^4.5.5",
     "typescript-json-schema": "^0.32.0"
   },
   "dependencies": {

scripts/run-fixtures.js

@@ -5,7 +5,7 @@
 
 // Toggle this on to update the JSON files for each run
 // or use `yarn test:update-fixtures`
-const writeResults = false || process.argv.includes('--update')
+const writeResults = false || process.argv.includes("--update")
 
 const fs = require("fs")
 const child_process = require("child_process")
@@ -32,7 +32,7 @@ const fixtures = fs
 
 let runCount = 0
 
-console.log("Running Fixures for Danger JS. This uses the built version of danger.\n")
+console.log("Running Fixtures for Danger JS. This uses the built version of danger.\n")
 
 // Runs the danger runner over a fixture, then compares it to the
 // fixtured JSON data
@@ -107,7 +107,7 @@ const next = () => {
   }
 }
 
-process.on("unhandledRejection", function (reason, _p) {
+process.on("unhandledRejection", function(reason, _p) {
   console.log(chalk.red("Error: "), reason)
   process.exitCode = 1
 })

source/platforms/gitlab/GitLabAPI.ts

@@ -237,7 +237,7 @@ class GitLabAPI {
     } catch (e) {
       this.d("getFileContents", e)
       // GitHubAPI.fileContents returns "" when the file does not exist, keep it consistent across providers
-      if (e.response.status === 404) {
+      if ((e as any).response.status === 404) {
         return ""
       }
       throw e

source/runner/Executor.ts

@@ -100,7 +100,7 @@ export class Executor {
     try {
       results = await this.runner.runDangerfileEnvironment([file], [undefined], runtime)
     } catch (error) {
-      results = this.resultsForError(error)
+      results = this.resultsForError(error as Error)
     }
 
     await this.handleResults(results, runtime.danger.git)

source/runner/runners/inline.ts

@@ -116,7 +116,7 @@ export const runDangerfileEnvironment = async (
       d("Got a parse error: ", error)
 
       // Call the internal functions to fail the build
-      const errorResults = resultsForCaughtError(filename, content, error)
+      const errorResults = resultsForCaughtError(filename, content, error as Error)
       environment.markdown(errorResults.markdowns[0].message)
       environment.fail(errorResults.fails[0].message)
     }