fix: Panics caused by BoundingBox API returning nil

[GuyGoldenberg]

The boundingBox playwright API may return nil for the bounding box without setting an error.
The Go implementation doesn't support this case, causing null dereference and panics when trying to remap the nil to the matching struct.

We handle this by checking if the value is nil before remapping values.

This PR fixes this bug by checking for nil value before remapping.

We can also change the implementation of the remapping but it will require passing pointer to a pointer (**) in order to set nil values for variables.

Reference - https://github.com/microsoft/playwright/blob/59a50cf59603850c645830a17ccb05178eb96f50/packages/playwright-core/src/client/elementHandle.ts#L185

Panic Trace

	/usr/local/go/src/runtime/panic.go:785 +0x124
reflect.flag.mustBe(...)
	/usr/local/go/src/reflect/value.go:218
reflect.Value.MapKeys({0x0?, 0x0?, 0x27f7f58?})
	/usr/local/go/src/reflect/value.go:1828 +0x1f4
github.com/playwright-community/playwright-go.remapValue({0x0?, 0x0?, 0x4003bd3c18?}, {0x209e2c0?, 0x4004203240?, 0x0?})
	/go/pkg/mod/github.com/playwright-community/[email protected]/helpers.go:161 +0x5c8
github.com/playwright-community/playwright-go.remapMapToStruct({0x0?, 0x0?}, {0x1b21b60?, 0x4004203240?})
	/go/pkg/mod/github.com/playwright-community/[email protected]/helpers.go:174 +0x100
github.com/playwright-community/playwright-go.(*elementHandleImpl).BoundingBox(0x1b61a60?)
	/go/pkg/mod/github.com/playwright-community/[email protected]/element_handle.go:193 +0x84
github.com/playwright-community/playwright-go.(*locatorImpl).BoundingBox.func1({0x28f0108?, 0x4002b940a0?})
	/go/pkg/mod/github.com/playwright-community/[email protected]/locator.go:143 +0x2c
github.com/playwright-community/playwright-go.(*locatorImpl).withElement(0x4003bd3d18?, 0x24ba0d0, {0x4006773d40?, 0x1c3c3c0?, 0x1?})
	/go/pkg/mod/github.com/playwright-community/[email protected]/locator.go:846 +0x5c
github.com/playwright-community/playwright-go.(*locatorImpl).BoundingBox(0x40039ab230, {0x40066ccfb0?, 0x1?, 0x0?})
	/go/pkg/mod/github.com/playwright-community/[email protected]/locator.go:142 +0x8c
...
reflect: call of reflect.Value.MapKeys on zero Value

[mxschmitt]

do you mind adding a test for it? Ideally around here: https://github.com/playwright-community/playwright-go/blob/main/tests/element_handle_test.go

[GuyGoldenberg]

Sure, added a test (display: hidden) and added your reference