add a message when solidify is used with only-edges, this isn't properly supported.

also minor edits to py-api-ref
-- This line, and those below, will be ignored--

M    doc/python_api/sphinx_doc_gen.py
M    doc/python_api/rst/include__bmesh.rst
M    source/blender/modifiers/intern/MOD_solidify.c

doc/python_api/rst/include__bmesh.rst

@@ -42,7 +42,6 @@ For an overview of BMesh data types and how they reference each other see:
    TODO items are...
 
    * add access to BMesh **walkers**
-   * add api for calling BMesh operators (unrelated to bpy.ops)
    * add custom-data manipulation functions add/remove/rename.
 
 Example Script

doc/python_api/sphinx_doc_gen.py

@@ -1538,8 +1538,8 @@ def write_rst_contents(basepath):
         "mathutils", "mathutils.geometry", "mathutils.noise",
         # misc
         "bgl", "blf", "gpu", "aud", "bpy_extras",
-        # bmesh
-        "bmesh", "bmesh.types", "bmesh.utils", "bmesh.ops",
+        # bmesh, submodules are in own page
+        "bmesh",
         )
 
     for mod in standalone_modules:

source/blender/modifiers/intern/MOD_solidify.c

@@ -750,6 +750,10 @@ static DerivedMesh *applyModifier(
 		CDDM_calc_normals(result);
 	}
 
+	if (numFaces == 0 && numEdges != 0) {
+		modifier_setError(md, "Faces needed for useful output");
+	}
+
 	return result;
 }