Jetpack Analyzer throws warnings and notices with some code

#### Steps to reproduce the issue

1. When running a compatibility check between WC 3.9 and 4.0, we've encountered some notices and warnings, e.g.
For WooCommerce bookings:
```
PHP Notice: Undefined property: PhpParser\Node\Expr\Variable::$value in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 37

Notice: Undefined property: PhpParser\Node\Expr\Variable::$value in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 37
PHP Warning: get_class() expects parameter 1 to be object, int given in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Utils.php on line 87

Warning: get_class() expects parameter 1 to be object, int given in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Utils.php on line 87
PHP Notice: Undefined property: PhpParser\Node\Expr\Variable::$value in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 37

Notice: Undefined property: PhpParser\Node\Expr\Variable::$value in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 37
PHP Notice: Undefined property: PhpParser\Node\Expr\Variable::$value in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 37

Notice: Undefined property: PhpParser\Node\Expr\Variable::$value in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 37
```
For multilingualpress:
```
PHP Notice: Undefined property: PhpParser\Node\Expr\Closure::$parts in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39

Notice: Undefined property: PhpParser\Node\Expr\Closure::$parts in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39
PHP Warning: implode(): Invalid arguments passed in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39

Warning: implode(): Invalid arguments passed in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39
PHP Notice: Undefined property: PhpParser\Node\Expr\PropertyFetch::$parts in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39

Notice: Undefined property: PhpParser\Node\Expr\PropertyFetch::$parts in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39
PHP Warning: implode(): Invalid arguments passed in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39

Warning: implode(): Invalid arguments passed in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39
PHP Notice: Undefined property: PhpParser\Node\Expr\PropertyFetch::$parts in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39

Notice: Undefined property: PhpParser\Node\Expr\PropertyFetch::$parts in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39
PHP Warning: implode(): Invalid arguments passed in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39

Warning: implode(): Invalid arguments passed in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 39
PHP Notice: Undefined property: PhpParser\Node\Expr\Variable::$value in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 37

Notice: Undefined property: PhpParser\Node\Expr\Variable::$value in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 37
PHP Notice: Undefined property: PhpParser\Node\Expr\Variable::$value in /Users/peter/Downloads/4.0-prep/compat-check/293a92400f02f4d2327e4eb5363248a9-98ac767bd76dca1eabb78fa21bd05ed6ca539d86/jetpack/packages/analyzer/src/Invocations/Visitor.php on line 37

```

#### What I expected
No notices and warning.

#### What happened instead
Some notices and warning.

Ref:
pb22l9-5V-p2

Start with packages/analyzer/src/Invocations/Visitor.php at lines 37 and 39, then inspect packages/analyzer/src/Utils.php at line 87. Run the compatibility check between WooCommerce 3.9 and 4.0 using the reported WooCommerce Bookings and MultilingualPress cases. Done means those cases complete without PHP notices or warnings.

Written by the indexing model from the issue text.