TrustKit through exception: Tried to generate the SPKI hash for an unsupported key algorithm

Question

The exception

Tried to generate the SPKI hash for an unsupported key algorithm

happens a lot to a very small amount of our users. Is this a bug or is TrustKit doing its job against potential hackers?

Call stack:

0  CoreFoundation                 0x1848d2d8c __exceptionPreprocess
1  libobjc.A.dylib                0x183a8c5ec objc_exception_throw
2  TrustKit                       0x10453ba40 -[TSKSPKIHashCache hashSubjectPublicKeyInfoFromCertificate:] (TSKSPKIHashCache.m:67)
3  TrustKit                       0x10453b188 verifyPublicKeyPin (ssl_pin_verifier.m:71)
4  TrustKit                       0x104542a88 -[TSKPinningValidator evaluateTrust:forHostname:] (TSKPinningValidator.m:126)
5  TrustKit                       0x104542e9c -[TSKPinningValidator handleChallenge:completionHandler:] (TSKPinningValidator.m:203)