fix: crash when using do loop with bad type

Author: boriel

src/api/check.py

@@ -12,6 +12,7 @@
 from src.api import config, errmsg, global_
 from src.api.constants import CLASS, SCOPE
 from src.symbols import sym as symbols
+from src.symbols.symbol_ import Symbol
 from src.symbols.type_ import Type
 
 __all__ = [
@@ -318,7 +319,7 @@ def is_number(*p):
     """Returns True if ALL the arguments are AST nodes
     containing NUMBER or numeric CONSTANTS
     """
-    return all(i.token in ("NUMBER", "CONST") and Type.is_numeric(i.type_) for i in p)
+    return all(isinstance(i, Symbol) and i.token in ("NUMBER", "CONST") and Type.is_numeric(i.type_) for i in p)
 
 
 def is_static_str(*p):

tests/functional/arch/zx48k/do_crash.bas

@@ -0,0 +1,2 @@
+DIM A AS UBYTE
+DO LOOP WHILE A = ""

tests/functional/cmdline/test_errmsg.txt

@@ -159,3 +159,8 @@ ND.Controls.bas:4: error: Invalid argument 'dirData'
 ND.Controls.bas:2: warning: [W150] Variable 'dirData' is never used
 >>> process_file('arch/zx48k/bad_fname_err4.bas', ['-S', '-q'])
 ND.Controls.bas:2: error: sub 'Controls_LABEL' declared but not implemented
+
+# DO LOOP type errors
+>>> process_file('arch/zx48k/do_crash.bas', ['-S', '-q'])
+do_crash.bas:2: error: Cannot convert string to a value. Use VAL() function
+do_crash.bas:2: warning: [W130] Empty loop