lazy: add assertions against common problems (#476)

* lazy: allow null package

* lazy: add assertions for common pitfalls

* lazy: pass plugin name to custom load function

* lazy: format description

Co-authored-by: raf <raf@notashelf.dev>

---------

Co-authored-by: raf <raf@notashelf.dev>

modules/wrapper/lazy/config.nix

@@ -3,7 +3,7 @@
   config,
   ...
 }: let
-  inherit (builtins) toJSON typeOf head length filter concatLists concatStringsSep;
+  inherit (builtins) toJSON typeOf head length filter concatLists concatStringsSep tryEval;
   inherit (lib.attrsets) mapAttrsToList;
   inherit (lib.modules) mkIf mkMerge;
   inherit (lib.generators) mkLuaInline;
@@ -21,10 +21,36 @@
         else keySpec.action;
     };
 
-  toLuaLznSpec = name: spec:
+  toLuaLznSpec = name: spec: let
+    packageName =
+      if typeOf spec.package == "string"
+      then spec.package
+      else if (spec.package ? pname && (tryEval spec.package.pname).success)
+      then spec.package.pname
+      else spec.package.name;
+  in
     (removeAttrs spec ["package" "setupModule" "setupOpts" "keys"])
     // {
-      "@1" = name;
+      "@1" =
+        if spec.package != null && packageName != name && spec.load == null
+        then
+          abort ''
+            vim.lazy.plugins.${name} does not match the package name ${packageName}.
+
+            Please either:
+            - rename it to vim.lazy.plugins.${packageName}, or
+            - if you intend to use a custom loader, specify a
+              vim.lazy.plugins.${name}.load function.
+          ''
+        else if spec.package == null && spec.load == null
+        then
+          abort ''
+            vim.lazy.plugins.${name} has null package but no load function given.
+
+            Please either specify a package, or (if you know what you're doing) provide a
+            custom load function.
+          ''
+        else name;
       beforeAll =
         if spec.beforeAll != null
         then
@@ -62,7 +88,7 @@
         if spec.load != null
         then
           mkLuaInline ''
-            funcion()
+            function(name)
               ${spec.load}
             end
           ''
@@ -76,7 +102,7 @@
     };
   lznSpecs = mapAttrsToList toLuaLznSpec cfg.plugins;
 
-  pluginPackages = mapAttrsToList (_: plugin: plugin.package) cfg.plugins;
+  pluginPackages = filter (x: x != null) (mapAttrsToList (_: plugin: plugin.package) cfg.plugins);
 
   specToNotLazyConfig = _: spec: ''
     do

modules/wrapper/lazy/lazy.nix

@@ -66,8 +66,12 @@
   lznPluginType = submodule {
     options = {
       package = mkOption {
-        type = pluginType;
+        type = nullOr pluginType;
-        description = "Plugin package";
+        description = ''
+          Plugin package.
+
+          If null, a custom load function must be provided
+        '';
       };
 
       setupModule = mkOption {
@@ -173,7 +177,7 @@
         description = ''
           Lua code to override the `vim.g.lz_n.load()` function for a single plugin.
 
-          This will be wrapped in a function.
+          This will be wrapped in a `function(name) ... end`.
         '';
       };
     };