Guard against packages not present on the cache

There were some places that could have been nil, and the pcache might
just not contain an entry either. This change should guard against
these cases & use a default (no package) instead.

autocompletecontext.go

@@ -235,6 +235,16 @@ func (c *auto_complete_context) get_candidates_from_decl_alias(cc cursor_context
 	return
 }
 
+func (c *auto_complete_context) decl_package_import_path(decl *decl) string {
+	if decl == nil || decl.scope == nil {
+		return ""
+	}
+	if pkg, ok := c.pcache[decl.scope.pkgname]; ok {
+		return pkg.import_name
+	}
+	return ""
+}
+
 func (c *auto_complete_context) get_candidates_from_decl(cc cursor_context, class decl_class, b *out_buffers) {
 	if cc.decl.is_alias() {
 		c.get_candidates_from_decl_alias(cc, class, b)
@@ -252,25 +262,19 @@ func (c *auto_complete_context) get_candidates_from_decl(cc cursor_context, clas
 				continue
 			}
 		}
-		pkgname := ""
-		if pkg, ok := c.pcache[decl.scope.pkgname]; ok {
-			pkgname = pkg.import_name
-		}
-		b.append_decl(cc.partial, decl.name, pkgname, decl, class)
+		b.append_decl(cc.partial, decl.name, c.decl_package_import_path(decl), decl, class)
 	}
 	// propose all children of an underlying struct/interface type
 	adecl := advance_to_struct_or_interface(cc.decl)
 	if adecl != nil && adecl != cc.decl {
 		for _, decl := range adecl.children {
 			if decl.class == decl_var {
-				pkgname := c.pcache[decl.name].import_name
-				b.append_decl(cc.partial, decl.name, pkgname, decl, class)
+				b.append_decl(cc.partial, decl.name, c.decl_package_import_path(decl), decl, class)
 			}
 		}
 	}
 	// propose all children of its embedded types
-	pkgname := c.pcache[cc.decl.name].import_name
-	b.append_embedded(cc.partial, cc.decl, pkgname, class)
+	b.append_embedded(cc.partial, cc.decl, c.decl_package_import_path(cc.decl), class)
 }
 
 func (c *auto_complete_context) get_import_candidates(partial string, b *out_buffers) {