fix: Fatal SERVERPOD error in 'serverpod generate'. (serverpod#2975)

tools/serverpod_cli/lib/src/analyzer/dart/endpoint_analyzers/endpoint_method_analyzer.dart

@@ -6,7 +6,7 @@ import 'package:serverpod_cli/src/analyzer/dart/endpoint_analyzers/endpoint_para
 import 'package:serverpod_cli/src/analyzer/dart/definitions.dart';
 import 'package:serverpod_cli/src/analyzer/dart/element_extensions.dart';
 import 'package:serverpod_cli/src/generator/types.dart';
-import 'package:serverpod_cli/src/analyzer/dart/endpoint_analyzers/keywords.dart';
+import 'extension/endpoint_parameters_extension.dart';
 
 const _excludedMethodNameSet = {
   'streamOpened',
@@ -32,8 +32,7 @@ abstract class EndpointMethodAnalyzer {
         name: method.name,
         documentationComment: method.documentationComment,
         annotations: _parseAnnotations(dartElement: method),
-        // TODO: Move removal of session parameter to Parameter analyzer
-        parameters: parameters.required.sublist(1), // Skip session parameter,
+        parameters: parameters.required,
         parametersNamed: parameters.named,
         parametersPositional: parameters.positional,
         returnType: TypeDefinition.fromDartType(method.returnType),
@@ -44,8 +43,7 @@ abstract class EndpointMethodAnalyzer {
       name: method.name,
       documentationComment: method.documentationComment,
       annotations: _parseAnnotations(dartElement: method),
-      // TODO: Move removal of session parameter to Parameter analyzer
-      parameters: parameters.required.sublist(1), // Skip session parameter,
+      parameters: parameters.required,
       parametersNamed: parameters.named,
       parametersPositional: parameters.positional,
       returnType: TypeDefinition.fromDartType(method.returnType),
@@ -72,9 +70,7 @@ abstract class EndpointMethodAnalyzer {
 
     if (_excludedMethodNameSet.contains(method.name)) return false;
 
-    if (_missingSessionParameter(method.parameters)) return false;
-
-    return true;
+    return method.parameters.isFirstRequiredParameterSession;
   }
 
   /// Validates the [MethodElement] and returns a list of
@@ -91,17 +87,6 @@ abstract class EndpointMethodAnalyzer {
     return errors.whereType<SourceSpanSeverityException>().toList();
   }
 
-  static bool _missingSessionParameter(List<ParameterElement> parameters) {
-    if (parameters.isEmpty) return true;
-
-    bool firstParameterIsNotSession =
-        parameters.first.type.element?.displayName != Keyword.sessionClassName;
-
-    return firstParameterIsNotSession ||
-        parameters.first.isNamed ||
-        parameters.first.isOptional;
-  }
-
   static SourceSpanSeverityException? _validateReturnType({
     required DartType dartType,
     required Element dartElement,

tools/serverpod_cli/lib/src/analyzer/dart/endpoint_analyzers/endpoint_parameter_analyzer.dart

@@ -4,7 +4,8 @@ import 'package:analyzer/dart/element/type.dart';
 import 'package:serverpod_cli/src/analyzer/code_analysis_collector.dart';
 import 'package:serverpod_cli/src/analyzer/dart/definitions.dart';
 import 'package:serverpod_cli/src/analyzer/dart/element_extensions.dart';
-import 'package:serverpod_cli/src/analyzer/dart/endpoint_analyzers/keywords.dart';
+import 'package:serverpod_cli/src/analyzer/dart/endpoint_analyzers/extension/endpoint_parameters_extension.dart';
+
 import 'package:serverpod_cli/src/generator/types.dart';
 
 abstract class EndpointParameterAnalyzer {
@@ -17,7 +18,8 @@ abstract class EndpointParameterAnalyzer {
     var positionalParameters = <ParameterDefinition>[];
     var namedParameters = <ParameterDefinition>[];
 
-    for (var parameter in parameters) {
+    var filteredParameters = parameters.withoutSessionParameter;
+    for (var parameter in filteredParameters) {
       var definition = ParameterDefinition(
         name: parameter.name,
         required: _isRequired(parameter),
@@ -46,18 +48,25 @@ abstract class EndpointParameterAnalyzer {
   ) {
     List<SourceSpanSeverityException> exceptions = [];
 
-    bool firstParameterIsSession = parameters.isNotEmpty &&
-        parameters.first.type.element?.displayName == Keyword.sessionClassName;
-
-    if (firstParameterIsSession) {
-      bool sessionIsNullable =
-          parameters.first.type.nullabilitySuffix != NullabilitySuffix.none;
-      if (sessionIsNullable) {
-        exceptions.add(SourceSpanSeverityException(
-            'The "Session" argument in an endpoint method does not have to be nullable, consider making it non-nullable.',
-            parameters.first.span,
-            severity: SourceSpanSeverity.hint));
-      }
+    if (!parameters.isFirstRequiredParameterSession) {
+      exceptions.add(
+        SourceSpanSeverityException(
+          'The first parameter of an endpoint method must be a required positional parameter of type "Session".',
+          parameters.first.span,
+          severity: SourceSpanSeverity.error,
+        ),
+      );
+      return exceptions;
+    }
+
+    if (parameters.isSessionParameterNullable) {
+      exceptions.add(
+        SourceSpanSeverityException(
+          'The "Session" argument in an endpoint method does not have to be nullable, consider making it non-nullable.',
+          parameters.first.span,
+          severity: SourceSpanSeverity.hint,
+        ),
+      );
     }
 
     exceptions.addAll(parameters.map((parameter) {

tools/serverpod_cli/lib/src/analyzer/dart/endpoint_analyzers/extension/endpoint_parameters_extension.dart

@@ -0,0 +1,27 @@
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/nullability_suffix.dart';
+import 'package:serverpod_cli/src/analyzer/dart/endpoint_analyzers/keywords.dart';
+
+/// Extension for [List<ParameterElement>] to analyze endpoint parameters.
+extension EndpointParametersExtension on List<ParameterElement> {
+  /// Returns true if the first required parameter is a session parameter.
+  bool get isFirstRequiredParameterSession {
+    if (isEmpty) return false;
+
+    var parameter = first;
+
+    return parameter.type.element?.displayName == Keyword.sessionClassName &&
+        parameter.isRequiredPositional;
+  }
+
+  bool get isSessionParameterNullable {
+    return first.type.nullabilitySuffix != NullabilitySuffix.none;
+  }
+
+  /// Returns a list of parameters without the session parameter.
+  List<ParameterElement> get withoutSessionParameter {
+    return where((parameter) =>
+            parameter.type.element?.displayName != Keyword.sessionClassName)
+        .toList();
+  }
+}