fix: check t[k] should not warn unnecessary-if

crates/emmylua_code_analysis/src/diagnostic/test/unnecessary_if_test.rs

@@ -26,4 +26,21 @@ mod test {
         "#
         ));
     }
+
+    #[test]
+    fn test_table_generic_index_not_unnecessary() {
+        let mut ws = VirtualWorkspace::new();
+        assert!(ws.check_code_for(
+            DiagnosticCode::UnnecessaryIf,
+            r#"
+        ---@type table<string, number>
+        local t = {}
+        local k = "hello"
+        local v = t[k]
+        if v then
+            print(v)
+        end
+        "#
+        ));
+    }
 }

crates/emmylua_code_analysis/src/semantic/infer/infer_index/mod.rs

@@ -1110,7 +1110,8 @@ fn infer_member_by_index_table_generic(
     let index_key = index_expr.get_index_key().ok_or(InferFailReason::None)?;
     let key_type = &table_params[0];
     let value_type = &table_params[1];
-    infer_index_metamethod(db, cache, &index_key, key_type, value_type)
+    let result = infer_index_metamethod(db, cache, &index_key, key_type, value_type)?;
+    Ok(TypeOps::Union.apply(db, &result, &LuaType::Nil))
 }
 
 fn infer_global_field_member(

crates/emmylua_code_analysis/src/semantic/member/infer_raw_member.rs

@@ -200,7 +200,7 @@ fn infer_table_generic_raw_member_type(
         LuaMemberKey::None => return Err(InferFailReason::FieldNotFound),
     };
     if check_type_compact(db, key_type, &access_key_type).is_ok() {
-        return Ok(value_type.clone());
+        return Ok(TypeOps::Union.apply(db, value_type, &LuaType::Nil));
     }
 
     Err(InferFailReason::FieldNotFound)

crates/emmylua_ls/src/handlers/test/hover_test.rs

@@ -271,7 +271,7 @@ mod tests {
                 end
             "#,
             VirtualHoverResult {
-                value: "```lua\n(field) _cfg: number\n```".to_string(),
+                value: "```lua\n(field) _cfg: number?\n```".to_string(),
             },
         ));
 
@@ -293,7 +293,7 @@ mod tests {
                 end
             "#,
             VirtualHoverResult {
-                value: "```lua\n(field) _cfg: number\n```".to_string(),
+                value: "```lua\n(field) _cfg: number?\n```".to_string(),
             },
         ));
         Ok(())