GrailsExceptionResolver masks original exception with GrailsWebRequest cast failure

[jamesfredley]

Description

GrailsExceptionResolver can mask the original application exception when Spring's RequestContextHolder contains a plain ServletRequestAttributes rather than a GrailsWebRequest.

During status-code mapping, AbstractUrlMappingInfo.evaluateNameForValue unconditionally casts the current request attributes to GrailsWebRequest. The resulting ClassCastException replaces the original exception and does not preserve it as a cause.

Reproduction

Using the official Grails 8.0.0-M5 distribution, bind a plain ServletRequestAttributes and call the public exception resolver with an explicit application exception:

RequestContextHolder.setRequestAttributes(
    new ServletRequestAttributes(new MockHttpServletRequest(), new MockHttpServletResponse())
)

def original = new IllegalStateException('ORIGINAL_EXCEPTION')
exceptionResolver.resolveException(request, response, null, original)

A full Spring MockMvc dispatch also reproduces the condition because MockMvc binds ServletRequestAttributes. Grails encounters an earlier handler-lookup error, then replaces that error with the same cast failure while resolving it.

Actual behavior

java.lang.ClassCastException: class org.springframework.web.context.request.ServletRequestAttributes cannot be cast to class org.grails.web.servlet.mvc.GrailsWebRequest
    at org.grails.web.mapping.AbstractUrlMappingInfo.evaluateNameForValue(AbstractUrlMappingInfo.java:124)
    at org.grails.web.mapping.DefaultUrlMappingInfo.getNamespace(DefaultUrlMappingInfo.java:189)
    at org.grails.web.mapping.mvc.AbstractGrailsControllerUrlMappings.collectControllerMapping(AbstractGrailsControllerUrlMappings.groovy:267)
    at org.grails.web.mapping.mvc.AbstractGrailsControllerUrlMappings.matchStatusCode(AbstractGrailsControllerUrlMappings.groovy:145)
    at org.grails.web.errors.GrailsExceptionResolver.matchStatusCode(GrailsExceptionResolver.java:267)
    at org.grails.web.errors.GrailsExceptionResolver.resolveViewOrForward(GrailsExceptionResolver.java:196)
    at org.grails.web.errors.GrailsExceptionResolver.resolveException(GrailsExceptionResolver.java:113)

The ClassCastException has no cause, so the original IllegalStateException("ORIGINAL_EXCEPTION") is lost.

Expected behavior

Exception resolution should not assume every RequestAttributes implementation is a GrailsWebRequest. It should preserve and resolve the original exception, or safely treat Grails-specific URL mapping values as unavailable when the current attributes are not a GrailsWebRequest.

Environment

• Grails: 8.0.0-M5
• Groovy: 5.0.8
• Spring Framework: 7.0.8
• Spring Boot: 4.1.0
• Java: 21.0.11

The isolated application build passed with both reproduction tests, including the full MockMvc path and direct public resolver path.