Fix PSalm errors

Author: byjg

.run/PSalm.run.xml

@@ -0,0 +1,5 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="PSalm" type="PhpLocalRunConfigurationType" factoryName="PHP Console" path="$PROJECT_DIR$/vendor/bin/psalm">
+    <method v="2" />
+  </configuration>
+</component>

.run/Test Project.run.xml

@@ -0,0 +1,6 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="Test Project" type="PHPUnitRunConfigurationType" factoryName="PHPUnit">
+    <TestRunner configuration_file="$PROJECT_DIR$/phpunit.xml.dist" scope="XML" use_alternative_configuration_file="true" />
+    <method v="2" />
+  </configuration>
+</component>

src/AnyDataset.php

@@ -175,20 +175,13 @@ public function save(?string $filename = null): void
      */
     public function appendRow(Row|array $singleRow = []): void
     {
-        if (!empty($singleRow)) {
-            if ($singleRow instanceof Row) {
-                $this->collection[] = $singleRow;
-                $singleRow->acceptChanges();
-            } elseif (is_array($singleRow)) {
-                $this->collection[] = new Row($singleRow);
-            } else {
-                throw new InvalidArgumentException("You must pass an array or a Row object");
-            }
-        } else {
+        if (empty($singleRow)) {
             $singleRow = new Row();
-            $this->collection[] = $singleRow;
-            $singleRow->acceptChanges();
+        } elseif (is_array($singleRow)) {
+            $singleRow = new Row($singleRow);
         }
+
+        $this->collection[] = $singleRow;
         $this->currentRow = count($this->collection) - 1;
     }
 

src/RowOutput.php

@@ -93,7 +93,7 @@ protected function formatCustom(Row $row, string $field, Closure $closure): stri
     /**
      * @param string $field
      * @param string $pattern
-     * @return RowOutput
+     * @return static
      */
     public function addFormat(string $field, string $pattern): static
     {
@@ -104,7 +104,7 @@ public function addFormat(string $field, string $pattern): static
     /**
      * @param string $field
      * @param Closure $closure
-     * @return RowOutput
+     * @return static
      */
     public function addCustomFormat(string $field, Closure $closure): static
     {