Better error message when vocab top level forms leave crap on the stack

core/vocabs/loader/loader-tests.factor

@@ -1,9 +1,9 @@
-! Unit tests for vocabs.loader vocabulary
 IN: vocabs.loader.tests
 USING: vocabs.loader tools.test continuations vocabs math
 kernel arrays sequences namespaces io.streams.string
 parser source-files words assocs classes.tuple definitions
-debugger compiler.units tools.vocabs accessors eval ;
+debugger compiler.units tools.vocabs accessors eval
+combinators ;
 
 ! This vocab should not exist, but just in case...
 [ ] [
@@ -151,3 +151,8 @@ forget-junk
 [ "xabbabbja" forget-vocab ] with-compilation-unit
 
 forget-junk
+
+[ ] [ [ "vocabs.loader.test.e" forget-vocab ] with-compilation-unit ] unit-test
+
+[ "vocabs.loader.test.e" require ]
+[ relative-overflow? ] must-fail-with

core/vocabs/loader/loader.factor

@@ -55,7 +55,7 @@ SYMBOL: load-help?
     f over set-vocab-source-loaded?
     [ vocab-source-path [ parse-file ] [ [ ] ] if* ] keep
     t swap set-vocab-source-loaded?
-    [ % ] [ call ] if-bootstrapping ;
+    [ % ] [ assert-depth ] if-bootstrapping ;
 
 : load-docs ( vocab -- vocab )
     load-help? get [

core/vocabs/loader/test/e/e.factor

@@ -0,0 +1 @@
+1 2 3

core/vocabs/loader/test/e/tags.txt

@@ -0,0 +1 @@
+unportable