src,lib: print prinstine source when source map source not found

Print unmapped source lines when the source map source is not
found. Error stacks should be correctly mapped even when the
source is absent.

PR-URL: #44052
Refs: #44019
Reviewed-By: Ben Coe <bencoe@gmail.com>

lib/internal/source_map/prepare_stack_trace.js

@@ -139,17 +139,21 @@ function getErrorSource(
   originalLine,
   originalColumn
 ) {
-  let exceptionLine = '';
   const originalSourcePathNoScheme =
     StringPrototypeStartsWith(originalSourcePath, 'file://') ?
       fileURLToPath(originalSourcePath) : originalSourcePath;
   const source = getOriginalSource(
     sourceMap.payload,
     originalSourcePath
   );
+  if (typeof source !== 'string') {
+    return;
+  }
   const lines = RegExpPrototypeSymbolSplit(/\r?\n/, source, originalLine + 1);
   const line = lines[originalLine];
-  if (!line) return exceptionLine;
+  if (!line) {
+    return;
+  }
 
   // Display ^ in appropriate position, regardless of whether tabs or
   // spaces are used:
@@ -161,7 +165,7 @@ function getErrorSource(
   }
   prefix = StringPrototypeSlice(prefix, 0, -1); // The last character is '^'.
 
-  exceptionLine =
+  const exceptionLine =
    `${originalSourcePathNoScheme}:${originalLine + 1}\n${line}\n${prefix}^\n\n`;
   return exceptionLine;
 }
@@ -184,10 +188,7 @@ function getOriginalSource(payload, originalSourcePath) {
       source = readFileSync(originalSourcePathNoScheme, 'utf8');
     } catch (err) {
       debug(err);
-      source = '';
     }
-  } else {
-    source = '';
   }
   return source;
 }

src/node_errors.cc

@@ -105,7 +105,9 @@ static std::string GetErrorSource(Isolate* isolate,
   if (has_source_map_url && env != nullptr && env->source_maps_enabled()) {
     std::string source = GetSourceMapErrorSource(
         isolate, context, message, added_exception_line);
-    return *added_exception_line ? source : sourceline;
+    if (*added_exception_line) {
+      return source;
+    }
   }
 
   // Because of how node modules work, all scripts are wrapped with a

test/fixtures/source-map/no-source.ts

@@ -0,0 +1,10 @@
+function Throw() {
+  throw new Error('foo');
+}
+
+Throw();
+
+// To recreate:
+//
+// npx tsc --outDir test/fixtures/source-map --sourceMap test/fixtures/source-map/no-source.ts
+// rename the "source.[0]" to "file-not-exists.ts"

test/message/source_map_no_source_file.js

@@ -0,0 +1,6 @@
+// Flags:  --enable-source-maps
+
+'use strict';
+require('../common');
+
+require('../fixtures/source-map/no-source.js');

test/message/source_map_no_source_file.out

@@ -0,0 +1,17 @@
+*no-source.js:2
+    throw new Error('foo');
+    ^
+
+Error: foo
+    at Throw (*file-not-exists.ts:2:9)
+    at Object.<anonymous> (*file-not-exists.ts:5:1)
+    at Module._compile (node:internal/modules/cjs/loader:*)
+    at Module._extensions..js (node:internal/modules/cjs/loader:*)
+    at Module.load (node:internal/modules/cjs/loader:*)
+    at Module._load (node:internal/modules/cjs/loader:*)
+    at Module.require (node:internal/modules/cjs/loader:*)
+    at require (node:internal/modules/cjs/helpers:*)
+    at Object.<anonymous> (*source_map_no_source_file.js:6:1)
+    at Module._compile (node:internal/modules/cjs/loader:*)
+
+Node.js *