rename errorWithNode to buildCodeFrameError and when erroring on dynamic nodes try and estimate a location

packages/babel-core/src/transformation/file/index.js

@@ -20,6 +20,15 @@ import * as util from  "../../util";
 import path from "path";
 import * as t from "babel-types";
 
+var errorVisitor = {
+  enter(path, state) {
+    var loc = path.node.loc;
+    if (loc) {
+      state.loc = loc;
+      path.stop();
+    }
+  }
+};
 export default class File {
   constructor(opts = {}, pipeline) {
     this.pipeline = pipeline;
@@ -383,17 +392,26 @@ export default class File {
     return uid;
   }
 
-  errorWithNode(node, msg, Error = SyntaxError) {
+  buildCodeFrameError(node, msg, Error = SyntaxError) {
-    var err;
     var loc = node && (node.loc || node._loc);
+
+    var err = new Error(msg);
+
     if (loc) {
-      err = new Error(`Line ${loc.start.line}: ${msg}`);
       err.loc = loc.start;
     } else {
-      // todo: find errors with nodes inside to at least point to something
+      traverse(node, errorVisitor, err);
-      err = new Error("There's been an error on a dynamic node. This is almost certainly an internal error. Please report it.");
+
+      err.message += " (This is an error on an internal node. Probably an internal error";
+
+      if (err.loc) {
+        err.message += ". Location has been estimated.";
+      }
+
+      err.message += ")";
     }
-    return err;
+
+    return err
   }
 
   mergeSourceMap(map: Object) {

packages/babel-core/src/transformation/helpers/define-map.js

@@ -28,7 +28,7 @@ export function push(mutatorMap, node, kind, file) {
   }
 
   if (map.value || map.initializer) {
-    throw file.errorWithNode(node, "Key conflict with sibling node");
+    throw file.buildCodeFrameError(node, "Key conflict with sibling node");
   }
 
   if (node.value) {

packages/babel-core/src/transformation/modules/_default.js

@@ -37,7 +37,7 @@ export default class DefaultFormatter {
 
     var existingScope = this.sourceScopes[source];
     if (existingScope && existingScope !== path.scope) {
-      throw path.errorWithNode(messages.get("modulesDuplicateDeclarations"));
+      throw path.buildCodeFrameError(messages.get("modulesDuplicateDeclarations"));
     }
 
     this.sourceScopes[source] = path.scope;
@@ -180,7 +180,7 @@ export default class DefaultFormatter {
 
   checkExportIdentifier(node) {
     if (t.isIdentifier(node, { name: "__esModule" })) {
-      throw this.file.errorWithNode(node, messages.get("modulesIllegalExportName", node.name));
+      throw this.file.buildCodeFrameError(node, messages.get("modulesIllegalExportName", node.name));
     }
   }