Verify REL module tyoe before loading

src/vmsrc/apple/cmd.pla

@@ -1064,6 +1064,13 @@ def loadmod(mod)#1
         refnum = open(strcpy(@filename,strcat(strcpy(@header, @sysmods), @filename)))
     fin
     if refnum
+        header.0 = $0A
+        header:1 = @filename
+        if not syscall($C4, @header) and header.4 <> $FE // Make sure it's a REL module
+            close(refnum)
+            perr = $4A // Incompatible type
+            return -perr
+        fin
         rdlen   = read(refnum, @header, 128)
         modsize = header:0
         moddep  = @header.1