feat(ext/console): Display error.cause in console (#12462)

2 files changed, 63 insertions, 1 deletions

diff --git a/cli/tests/unit/console_test.ts b/cli/tests/unit/console_test.ts
index b5dcf2f05..4201a2a46 100644
--- a/cli/tests/unit/console_test.ts
+++ b/cli/tests/unit/console_test.ts
@@ -1823,6 +1823,48 @@ unitTest(function inspectProxy() {
   );
 });
 
+unitTest(function inspectError() {
+  const error1 = new Error("This is an error");
+  const error2 = new Error("This is an error", {
+    cause: new Error("This is a cause error"),
+  });
+
+  assertStringIncludes(
+    stripColor(Deno.inspect(error1)),
+    "Error: This is an error",
+  );
+  assertStringIncludes(
+    stripColor(Deno.inspect(error2)),
+    "Error: This is an error",
+  );
+  assertStringIncludes(
+    stripColor(Deno.inspect(error2)),
+    "Caused by Error: This is a cause error",
+  );
+});
+
+unitTest(function inspectErrorCircular() {
+  const error1 = new Error("This is an error");
+  const error2 = new Error("This is an error", {
+    cause: new Error("This is a cause error"),
+  });
+  error1.cause = error1;
+  error2.cause.cause = error2;
+
+  assertStringIncludes(
+    stripColor(Deno.inspect(error1)),
+    "Error: This is an error",
+  );
+  assertStringIncludes(
+    stripColor(Deno.inspect(error2)),
+    "Error: This is an error",
+  );
+  assertStringIncludes(
+    stripColor(Deno.inspect(error2)),
+    "Caused by Error: This is a cause error",
+  );
+});
+
 unitTest(function inspectColors() {
   assertEquals(Deno.inspect(1), "1");
   assertStringIncludes(Deno.inspect(1, { colors: true }), "\x1b[");
diff --git a/ext/console/02_console.js b/ext/console/02_console.js
index 09d96fc09..8d650d8ec 100644
--- a/ext/console/02_console.js
+++ b/ext/console/02_console.js
@@ -883,6 +883,26 @@
     return red(RegExpPrototypeToString(value)); // RegExps are red
   }
 
+  function inspectError(value) {
+    const causes = [];
+
+    let err = value;
+    while (
+      err.cause instanceof Error && err.cause !== value &&
+      !ArrayPrototypeIncludes(causes, err.cause) // circular check
+    ) {
+      ArrayPrototypePush(causes, err.cause);
+      err = err.cause;
+    }
+
+    return `${value.stack}${
+      ArrayPrototypeJoin(
+        ArrayPrototypeMap(causes, (cause) => `\nCaused by ${cause.stack}`),
+        "",
+      )
+    }`;
+  }
+
   function inspectStringObject(value, inspectOptions) {
     const cyan = maybeColor(colors.cyan, inspectOptions);
     return cyan(`[String: "${StringPrototypeToString(value)}"]`); // wrappers are in cyan
@@ -1141,7 +1161,7 @@
       return String(value[privateCustomInspect](inspect));
     }
     if (value instanceof Error) {
-      return String(value.stack);
+      return inspectError(value);
     } else if (ArrayIsArray(value)) {
       return inspectArray(value, level, inspectOptions);
     } else if (value instanceof Number) {