Drop unused ConeTypeMismatchError

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/coneDiagnosticToFirDiagnostic.kt

@@ -46,7 +46,6 @@ private fun ConeDiagnostic.toFirDiagnostic(
         is FirBackingFieldSymbol -> FirErrors.VAL_REASSIGNMENT_VIA_BACKING_FIELD_ERROR.on(source, symbol.fir.symbol)
         else -> FirErrors.VAL_REASSIGNMENT.on(source, symbol)
     }
-    is ConeTypeMismatchError -> FirErrors.TYPE_MISMATCH.on(qualifiedAccessSource ?: source, this.expectedType, this.actualType)
     is ConeUnexpectedTypeArgumentsError -> FirErrors.TYPE_ARGUMENTS_NOT_ALLOWED.on(this.source.safeAs() ?: source)
     is ConeIllegalAnnotationError -> FirErrors.NOT_AN_ANNOTATION_CLASS.on(source, this.name.asString())
     is ConeWrongNumberOfTypeArgumentsError ->

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/diagnostics/FirDiagnostics.kt

@@ -74,11 +74,6 @@ class ConeValReassignmentError(val variable: FirVariableSymbol<*>) : ConeDiagnos
     override val reason: String get() = "Re-assigning a val variable"
 }
 
-class ConeTypeMismatchError(val expectedType: ConeKotlinType, val actualType: ConeKotlinType) : ConeDiagnostic() {
-    override val reason: String
-        get() = "Type mismatch. Expected: $expectedType, Actual: $actualType"
-}
-
 class ConeContractDescriptionError(override val reason: String) : ConeDiagnostic()
 
 class ConeIllegalAnnotationError(val name: Name) : ConeDiagnostic() {