fix(lsp): walk assignment target bases for name diagnostics

`_x.a = 1`, `_x.a += 2`, `_x[0] = 3` and `_x.a: T = v` only visited the assigned value, so an unresolved target base never produced the unknown-name warning.

App/lib/lsp/LspChecks.vp

@@ -1582,6 +1582,12 @@ def _WalkChecks(pool: memhub.MemManager*, doc: LspDocuments.LspDocument*,
                          or dst.kind == LspTypes.LT_AGG or dst.kind == LspTypes.LT_UNKNOWN):
                 _EmitTypeError(pool, doc, an.value,
                     "a pointer/`own` value cannot be stored into a value-typed variable; declare the target as `own T` / `T*`, or dereference explicitly (`*p`)", errors)
+            if an.target is not None and an.target.kind() == ast.ASTKind.Attribute:
+                _WalkChecksExprs(pool, doc, a, ws, table_pool, ast.Attribute*(an.target).value, errors)
+            elif an.target is not None and an.target.kind() == ast.ASTKind.Subscript:
+                sb_an: ast.Subscript* = ast.Subscript*(an.target)
+                _WalkChecksExprs(pool, doc, a, ws, table_pool, sb_an.value, errors)
+                _WalkChecksExprs(pool, doc, a, ws, table_pool, sb_an.slice, errors)
             if an.target is not None and an.target.kind() == ast.ASTKind.Name:
                 tn: ast.Name* = ast.Name*(an.target)
                 if tn.id is not None:
@@ -1599,7 +1605,17 @@ def _WalkChecks(pool: memhub.MemManager*, doc: LspDocuments.LspDocument*,
                 while ti < int(len(asn.targets)):
                     tgt: ast.AST* = asn.targets.get(sizet(ti))
                     ti += 1
-                    if tgt is None or tgt.kind() != ast.ASTKind.Name:
+                    if tgt is None:
+                        continue
+                    if tgt.kind() == ast.ASTKind.Attribute:
+                        _WalkChecksExprs(pool, doc, a, ws, table_pool, ast.Attribute*(tgt).value, errors)
+                        continue
+                    if tgt.kind() == ast.ASTKind.Subscript:
+                        sb_t: ast.Subscript* = ast.Subscript*(tgt)
+                        _WalkChecksExprs(pool, doc, a, ws, table_pool, sb_t.value, errors)
+                        _WalkChecksExprs(pool, doc, a, ws, table_pool, sb_t.slice, errors)
+                        continue
+                    if tgt.kind() != ast.ASTKind.Name:
                         continue
                     tt: LspIndex.LspTarget* = _TargetAtNode(ws, pool, table_pool, a, doc, tgt)
                     if tt is None or tt.detail is None:
@@ -1639,6 +1655,12 @@ def _WalkChecks(pool: memhub.MemManager*, doc: LspDocuments.LspDocument*,
             continue
         if k == ast.ASTKind.AugAssign:
             ag: ast.AugAssign* = ast.AugAssign*(s)
+            if ag.target is not None and ag.target.kind() == ast.ASTKind.Attribute:
+                _WalkChecksExprs(pool, doc, a, ws, table_pool, ast.Attribute*(ag.target).value, errors)
+            elif ag.target is not None and ag.target.kind() == ast.ASTKind.Subscript:
+                sb_ag: ast.Subscript* = ast.Subscript*(ag.target)
+                _WalkChecksExprs(pool, doc, a, ws, table_pool, sb_ag.value, errors)
+                _WalkChecksExprs(pool, doc, a, ws, table_pool, sb_ag.slice, errors)
             if ag.target is not None and ag.value is not None:
                 tt_a: LspIndex.LspTarget* = _TargetAtNode(ws, pool, table_pool, a, doc, ag.target)
                 if tt_a is not None and tt_a.detail is not None: