Don't crash if the root of a trace is a TypeParameter

ast/ksp/src/main/kotlin/me/tatarka/kotlin/ast/KSAst.kt

@@ -21,6 +21,7 @@ import com.google.devtools.ksp.symbol.KSFunctionDeclaration
 import com.google.devtools.ksp.symbol.KSPropertyDeclaration
 import com.google.devtools.ksp.symbol.KSType
 import com.google.devtools.ksp.symbol.KSTypeAlias
+import com.google.devtools.ksp.symbol.KSTypeParameter
 import com.google.devtools.ksp.symbol.KSTypeReference
 import com.google.devtools.ksp.symbol.KSValueParameter
 import com.google.devtools.ksp.symbol.Modifier
@@ -531,7 +532,12 @@ private class KSAstType private constructor(
         return if (type.isError) {
             typeRef.toString()
         } else {
-            typeRef.toTypeName().toString()
+            try {
+                typeRef.toTypeName().toString()
+            }
+            catch (_: Throwable) {
+                typeRef.toString()
+            }
         }.shortenPackage()
     }
 

kotlin-inject-compiler/test/src/test/kotlin/me/tatarka/inject/test/FailureTest.kt

@@ -1273,4 +1273,37 @@ class FailureTest {
             contains("Qualifier: @MyQualifier can only be applied to the outer type")
         }
     }
+
+    @ParameterizedTest
+    @EnumSource(Target::class)
+    fun fails_if_cannot_find_inject_or_provider_and_root_is_a_type_parameter(target: Target) {
+        val projectCompiler = ProjectCompiler(target, workingDir)
+
+        assertFailure {
+            projectCompiler.source(
+                "MyComponent.kt",
+                """
+                import me.tatarka.inject.annotations.Component
+                import me.tatarka.inject.annotations.Inject
+                import me.tatarka.inject.annotations.Provides
+
+                class Foo
+
+                @Inject class Bar(val foo: Foo)
+
+                interface DestinationComponent<C> {
+                  val c: C
+                  val cProvider: () -> C
+                }
+
+                @Inject class CType(val bar: Bar)
+
+                @Component
+                abstract class FooBarComponent : DestinationComponent<CType>
+                """.trimIndent()
+            ).compile()
+        }.output().all {
+            contains("e: [ksp] Cannot find an @Inject constructor or provider for: Foo")
+        }
+    }
 }