Fix trailing space in error message

Author: liufengyun

compiler/src/dotty/tools/dotc/reporting/MessageRendering.scala

@@ -104,7 +104,7 @@ trait MessageRendering {
     }
 
     msg.linesIterator
-      .map { line => " " * (offset - 1) + "|" + padding + line}
+      .map { line => " " * (offset - 1) + "|" + (if line.isEmpty then "" else padding + line) }
       .mkString(EOL)
   }
 

tests/neg-macros/i6976.check

@@ -5,5 +5,5 @@
   |    Exception occurred while executing macro expansion.
   |    scala.MatchError: Inlined(EmptyTree,List(),Literal(Constant(2))) (of class dotty.tools.dotc.ast.Trees$Inlined)
   |    	at playground.macros$.mcrImpl(Macro_1.scala:12)
-  |    
+  |
   | This location is in code that was inlined at Test_2.scala:5

tests/neg-macros/macro-class-not-found-1.check

@@ -4,5 +4,5 @@
   |  Exception occurred while executing macro expansion.
   |  java.lang.NoClassDefFoundError
   |  	at Foo$.aMacroImplementation(Foo.scala:8)
-  |  
+  |
   | This location is in code that was inlined at Bar.scala:4

tests/neg-macros/macro-class-not-found-2.check

@@ -4,5 +4,5 @@
   |  Exception occurred while executing macro expansion.
   |  java.lang.NoClassDefFoundError: this.is.not.a.Class
   |  	at Foo$.aMacroImplementation(Foo.scala:8)
-  |  
+  |
   | This location is in code that was inlined at Bar.scala:4