Figure.legend should not accept a list of spec files

Author: seisman

pygmt/src/legend.py

@@ -8,6 +8,7 @@
     build_arg_list,
     data_kind,
     fmt_docstring,
+    is_nonstr_iter,
     kwargs_to_strings,
     use_alias,
 )
@@ -77,7 +78,8 @@ def legend(self, spec=None, position="JTR+jTR+o0.2c", box="+gwhite+p1p", **kwarg
     with Session() as lib:
         if spec is None:
             specfile = ""
-        elif data_kind(spec) == "file":
+        elif data_kind(spec) == "file" and not is_nonstr_iter(spec):
+            # Is a file but not a list of files
             specfile = spec
         else:
             raise GMTInvalidInput(f"Unrecognized data type: {type(spec)}")