a better message if graphviz's dot/nodejs is not found in PATH (#21488)

* finish issue #21474: a better message if dot is not found locally when using gendepend

* fix a typo in compiler

* trim empty path reported in `findNodeJs`

* compiler/main.nim: switch raise to simply quit

compiler/nodejs.nim

@@ -7,4 +7,4 @@ proc findNodeJs*(): string {.inline.} =
     result = findExe("node")
   if result.len == 0:
     echo "Please install NodeJS first, see https://nodejs.org/en/download"
-    raise newException(IOError, "NodeJS not found in PATH: " & result)
+    raise newException(IOError, "NodeJS not found in PATH")