tools.errors: fix printing of errors with no associated source file

basis/tools/errors/errors-tests.factor

@@ -0,0 +1,20 @@
+USING: compiler.errors stack-checker.errors tools.test words ;
+IN: tools.errors
+
+DEFER: blah
+
+[ ] [
+    {
+        T{ compiler-error
+           { error
+             T{ inference-error
+                f
+                T{ do-not-compile f blah }
+                +compiler-error+
+                blah
+             }
+           }
+           { asset blah }
+        }
+    } errors.
+] unit-test

basis/tools/errors/errors.factor

@@ -14,9 +14,11 @@ M: source-file-error compute-restarts
 M: source-file-error error-help
     error>> error-help ;
 
+CONSTANT: +listener-input+ "<Listener input>"
+
 M: source-file-error summary
     [
-        [ file>> [ % ": " % ] [ "<Listener input>" % ] if* ]
+        [ file>> [ % ": " % ] [ +listener-input+ % ] if* ]
         [ line#>> [ # ] when* ] bi
     ] "" make
     ;
@@ -27,7 +29,7 @@ M: source-file-error error.
 : errors. ( errors -- )
     group-by-source-file sort-errors
     [
-        [ nl "==== " write print nl ]
+        [ nl "==== " write +listener-input+ or print nl ]
         [ [ nl ] [ error. ] interleave ]
         bi*
     ] assoc-each ;

basis/ui/tools/error-list/error-list.factor

@@ -4,14 +4,14 @@ USING: accessors arrays sequences sorting assocs colors.constants fry
 combinators combinators.smart combinators.short-circuit editors make
 memoize compiler.units fonts kernel io.pathnames prettyprint
 source-files.errors math.parser init math.order models models.arrow
-models.arrow.smart models.search models.mapping models.delay debugger namespaces
-summary locals ui ui.commands ui.gadgets ui.gadgets.panes
+models.arrow.smart models.search models.mapping models.delay debugger
+namespaces summary locals ui ui.commands ui.gadgets ui.gadgets.panes
 ui.gadgets.tables ui.gadgets.labeled ui.gadgets.tracks ui.gestures
 ui.operations ui.tools.browser ui.tools.common ui.gadgets.scrollers
 ui.tools.inspector ui.gadgets.status-bar ui.operations
 ui.gadgets.buttons ui.gadgets.borders ui.gadgets.packs
-ui.gadgets.labels ui.baseline-alignment ui.images
-compiler.errors calendar ;
+ui.gadgets.labels ui.baseline-alignment ui.images ui.tools.listener
+compiler.errors calendar tools.errors ;
 IN: ui.tools.error-list
 
 CONSTANT: source-file-icon
@@ -39,7 +39,7 @@ SINGLETON: source-file-renderer
 M: source-file-renderer row-columns
     drop first2 [
         [ source-file-icon ]
-        [ "<Listener input>" or ]
+        [ +listener-input+ or ]
         [ length number>string ] tri*
     ] output>array ;