Pipeline - Fix scanner.

Still needs error reporting when using # outside pipelines.

Author: Pokute

src/compiler/scanner.ts

@@ -2043,12 +2043,13 @@ namespace ts {
                                 tokenValue += scanIdentifierParts();
                             }
                             return token = SyntaxKind.PrivateIdentifier;
-                        }
-                        tokenValue = "#";
-                        if (/*isPipelineHack*/ true) {
+                        } else {
+                            tokenValue = "#";
+                            if (/*isInsidePipelineHack*/ false) {
+                                error(Diagnostics.Invalid_character /* Hack placeholder token outside pipeline. */);
+                            }
                             return token = SyntaxKind.Identifier;
                         }
-                        error(Diagnostics.Invalid_character);                        
                     default:
                         const identifierKind = scanIdentifier(ch, languageVersion);
                         if (identifierKind) {