refactor(ngcc): guard against a crash if source-map flattening fails (#35718)

Source-maps in the wild could be badly formatted,
causing the source-map flattening processing to fail
unexpectedly. Rather than causing the whole of ngcc
to crash, we gracefully fallback to just returning the
generated source-map instead.

PR Close #35718

packages/compiler-cli/ngcc/src/rendering/dts_renderer.ts

@@ -111,7 +111,7 @@ export class DtsRenderer {
     this.dtsFormatter.addImports(
         outputText, importManager.getAllImports(dtsFile.fileName), dtsFile);
 
-    return renderSourceAndMap(this.fs, dtsFile, outputText);
+    return renderSourceAndMap(this.logger, this.fs, dtsFile, outputText);
   }
 
   private getTypingsFilesToRender(

packages/compiler-cli/ngcc/src/rendering/renderer.ts

@@ -114,7 +114,7 @@ export class Renderer {
     }
 
     if (compiledFile || switchMarkerAnalysis || isEntryPoint) {
-      return renderSourceAndMap(this.fs, sourceFile, outputText);
+      return renderSourceAndMap(this.logger, this.fs, sourceFile, outputText);
     } else {
       return [];
     }

packages/compiler-cli/ngcc/src/rendering/source_maps.ts

@@ -12,6 +12,7 @@ import {FileSystem, absoluteFromSourceFile, basename, absoluteFrom} from '../../
 import {FileToWrite} from './utils';
 import {SourceFileLoader} from '../sourcemaps/source_file_loader';
 import {RawSourceMap} from '../sourcemaps/raw_source_map';
+import {Logger} from '../logging/logger';
 
 export interface SourceMapInfo {
   source: string;
@@ -24,23 +25,26 @@ export interface SourceMapInfo {
  * with an appropriate source-map comment pointing to the merged source-map.
  */
 export function renderSourceAndMap(
-    fs: FileSystem, sourceFile: ts.SourceFile, generatedMagicString: MagicString): FileToWrite[] {
+    logger: Logger, fs: FileSystem, sourceFile: ts.SourceFile,
+    generatedMagicString: MagicString): FileToWrite[] {
   const generatedPath = absoluteFromSourceFile(sourceFile);
   const generatedMapPath = absoluteFrom(`${generatedPath}.map`);
   const generatedContent = generatedMagicString.toString();
   const generatedMap: RawSourceMap = generatedMagicString.generateMap(
       {file: generatedPath, source: generatedPath, includeContent: true});
 
+  try {
     const loader = new SourceFileLoader(fs);
     const generatedFile = loader.loadSourceFile(
         generatedPath, generatedContent, {map: generatedMap, mapPath: generatedMapPath});
 
     const rawMergedMap: RawSourceMap = generatedFile.renderFlattenedSourceMap();
     const mergedMap = fromObject(rawMergedMap);
-
     if (generatedFile.sources[0]?.inline) {
       // The input source-map was inline so make the output one inline too.
-    return [{path: generatedPath, contents: `${generatedFile.contents}\n${mergedMap.toComment()}`}];
+      return [
+        {path: generatedPath, contents: `${generatedFile.contents}\n${mergedMap.toComment()}`}
+      ];
     } else {
       const sourceMapComment = generateMapFileComment(`${basename(generatedPath)}.map`);
       return [
@@ -48,4 +52,12 @@ export function renderSourceAndMap(
         {path: generatedMapPath, contents: mergedMap.toJSON()}
       ];
     }
+  } catch (e) {
+    logger.error(
+        `Error when flattening the source-map "${generatedMapPath}" for "${generatedPath}": ${e.toString()}`);
+    return [
+      {path: generatedPath, contents: generatedContent},
+      {path: generatedMapPath, contents: fromObject(generatedMap).toJSON()},
+    ];
+  }
 }