Rethrow errors instead of rewriting them

regex/compile.go

@@ -407,7 +407,7 @@ func shuntingYard(re string, flags ...ReFlag) ([]postfixNode, error) {
 			} else {
 				escapedNode, err := newEscapedNode(re_postfix[i], false)
 				if err != nil {
-					return nil, fmt.Errorf("invalid escape character in expression")
+					return nil, err
 				}
 				outQueue = append(outQueue, escapedNode)
 			}
@@ -575,7 +575,7 @@ func shuntingYard(re string, flags ...ReFlag) ([]postfixNode, error) {
 					} else {
 						escapedNode, err := newEscapedNode(re_postfix[i], true)
 						if err != nil {
-							return nil, fmt.Errorf("invalid escape character in character class")
+							return nil, err
 						}
 						chars = append(chars, escapedNode)
 						i++
@@ -627,7 +627,7 @@ func shuntingYard(re string, flags ...ReFlag) ([]postfixNode, error) {
 								case "word": // Word characters
 									nodeToAdd, _ = newEscapedNode('w', true) // This isn't going to error, so I suppress it
 								default:
-									return nil, fmt.Errorf("invalid POSIX character class")
+									return nil, err
 								}
 								chars = append(chars, nodeToAdd)
 								i = temp_i + len(posixClass) + 2 // Skip over the class name, the closing colon and the closing bracket