优化(CodeInjectIncrementalSourceGenerator):增强代码健壮性

新增对空值和异常情况的检查，避免潜在运行时错误
- 在流操作中新增对 null 的检查
- 在属性解析中新增对名称和参数的验证
- 确保文件路径和区域名称非空
- 提取占位符时过滤空值
- 在属性列表为空时直接返回 null

Author: RRQM

src/CodeInjectSourceGenerator/CodeInjectIncrementalSourceGenerator.cs

@@ -87,7 +87,9 @@ private static string GetEmbeddedResourceContent(string resourceName = null)
             using (var stream = assembly.GetManifestResourceStream(targetResource))
             {
                 if (stream == null)
+                {
                     return null;
+                }
 
                 using (var reader = new StreamReader(stream, Encoding.UTF8))
                 {
@@ -135,16 +137,22 @@ private static ClassToGenerate GetSemanticTargetForGeneration(GeneratorSyntaxCon
             foreach (var attributeData in classSymbol.GetAttributes())
             {
                 if (attributeData.AttributeClass?.Name != "RegionInjectAttribute")
+                {
                     continue;
+                }
 
                 if (attributeData.ConstructorArguments.Length < 2)
+                {
                     continue;
+                }
 
                 var filePath = attributeData.ConstructorArguments[0].Value?.ToString();
                 var regionName = attributeData.ConstructorArguments[1].Value?.ToString();
 
                 if (string.IsNullOrEmpty(filePath) || string.IsNullOrEmpty(regionName))
+                {
                     continue;
+                }
 
                 var placeholders = new List<string>();
 
@@ -155,7 +163,9 @@ private static ClassToGenerate GetSemanticTargetForGeneration(GeneratorSyntaxCon
                     {
                         var value = attributeData.ConstructorArguments[i].Value?.ToString();
                         if (!string.IsNullOrEmpty(value))
+                        {
                             placeholders.Add(value);
+                        }
                     }
                 }
 
@@ -172,7 +182,9 @@ private static ClassToGenerate GetSemanticTargetForGeneration(GeneratorSyntaxCon
                             {
                                 var stringValue = item.Value?.ToString();
                                 if (!string.IsNullOrEmpty(stringValue))
+                                {
                                     placeholders.Add(stringValue);
+                                }
                             }
                         }
                     }
@@ -185,7 +197,9 @@ private static ClassToGenerate GetSemanticTargetForGeneration(GeneratorSyntaxCon
             }
 
             if (attributes.Count == 0)
+            {
                 return null;
+            }
 
             return new ClassToGenerate(
                 classSymbol.Name,