Strict-send pathfinder returns non-existent paths.

[marcinx]

Describe the bug
Horizon returns non-existent paths on /paths/strict-send.

Have a look at https://horizon.stellar.org/paths/strict-send?destination_account=GASKYWPPQ2VSO6KNIPIRVXMSSDGZLYZQ67CDTLVXOXYDG26SPZ66EDCQ&source_asset_type=credit_alphanum4&source_asset_code=EUR&source_asset_issuer=GA4ARTT4HG4MYFFA3JJIVWLGE53PAHMKDBCBCNRHCSIR3KZP5BVNNTD6&source_amount=6.14

Amongst other non-existent paths it returns:

      {
        "source_asset_type": "credit_alphanum4",
        "source_asset_code": "EUR",
        "source_asset_issuer": "GA4ARTT4HG4MYFFA3JJIVWLGE53PAHMKDBCBCNRHCSIR3KZP5BVNNTD6",
        "source_amount": "6.1400000",
        "destination_asset_type": "native",
        "destination_amount": "1174.3516812",
        "path": [
          {
            "asset_type": "credit_alphanum4",
            "asset_code": "USD",
            "asset_issuer": "GDSRCV5VTM3U7Y3L6DFRP3PEGBNQMGOWSRTGSBWX6Z3H6C7JHRI4XFJP"
          },
          {
            "asset_type": "credit_alphanum4",
            "asset_code": "ETH",
            "asset_issuer": "GBVOL67TMUQBGL4TZYNMY3ZQ5WGQYFPFD5VJRWXR72VA33VFNL225PL5"
          },
          {
            "asset_type": "credit_alphanum4",
            "asset_code": "NGNT",
            "asset_issuer": "GAWODAROMJ33V5YDFY3NPYTHVYQG7MJXVJ2ND3AOGIHYRWINES6ACCPD"
          }
        ]
      }

When trying to execute a strict-send payment with this path and the destinationMin set to 1174.3516812 * 0.99 it returns op_too_few_offers.

What version are you on?
v0.22.1

To Reproduce
Fetch best paths per asset as given by /paths/strict-send and try to execute strict-send payments with the given destinationAmount (minus padding).

Expected behavior
Horizon should return existent paths only.

Additional context
Tried several paths given by /paths/strict-send, which seemed abnormally high and ran into op_too_few_offers every time.

When a path depth/length of 5 is used on Horizon (instead of the default 4, as on e.g. horizon.stellar.org) even more non-existent paths with astronomical "profits" are returned.

@bartekn @tamirms @tomquisel

[marcinx]

When a --max-path-length=5 is used, then Horizon returns "even better" non-existent paths with up to 19378 XLM for 6.14 EUR.

      {
        "source_asset_type": "credit_alphanum4",
        "source_asset_code": "EUR",
        "source_asset_issuer": "GA4ARTT4HG4MYFFA3JJIVWLGE53PAHMKDBCBCNRHCSIR3KZP5BVNNTD6",
        "source_amount": "6.1400000",
        "destination_asset_type": "native",
        "destination_amount": "19378.6001251",
        "path": [
          {
            "asset_type": "credit_alphanum4",
            "asset_code": "USD",
            "asset_issuer": "GDSRCV5VTM3U7Y3L6DFRP3PEGBNQMGOWSRTGSBWX6Z3H6C7JHRI4XFJP"
          },
          {
            "asset_type": "credit_alphanum4",
            "asset_code": "XLMG",
            "asset_issuer": "GCVNN7O5JISPEYUTLK3JYGBDWCPDIHB4MTG4PMSJVIKJCR64NOXWI3YH"
          },
          {
            "asset_type": "credit_alphanum4",
            "asset_code": "BTC",
            "asset_issuer": "GAUTUYY2THLF7SGITDFMXJVYH3LHDSMGEAKSBU267M2K7A3W543CKUEF"
          },
          {
            "asset_type": "credit_alphanum4",
            "asset_code": "BTC",
            "asset_issuer": "GATEMHCCKCY67ZUCKTROYN24ZYT5GK4EQZ65JJLDHKHRUZI3EUEKMTCH"
          }
        ]
      }

[tamirms]

fixed by #1863