Extract error messages to the constant

.dialyzer-ignore

@@ -27,8 +27,8 @@ lib/block_scout_web/templates/address_contract/index.html.eex:158
 lib/block_scout_web/templates/address_contract/index.html.eex:195
 lib/explorer/staking/stake_snapshotting.ex:15: Function do_snapshotting/7 has no local return
 lib/explorer/staking/stake_snapshotting.ex:147
-lib/explorer/third_party_integrations/sourcify.ex:70
 lib/explorer/third_party_integrations/sourcify.ex:73
+lib/explorer/third_party_integrations/sourcify.ex:76
 lib/block_scout_web/views/transaction_view.ex:137
 lib/block_scout_web/views/transaction_view.ex:152
 lib/block_scout_web/views/transaction_view.ex:197

apps/block_scout_web/lib/block_scout_web/controllers/address_contract_verification_controller.ex

@@ -198,10 +198,10 @@ defmodule BlockScoutWeb.AddressContractVerificationController do
         })
 
       {:error, :metadata} ->
-        return_sourcify_error(conn, "Sourcify did not return metadata", address_hash_string)
+        return_sourcify_error(conn, Sourcify.no_metadata_message(), address_hash_string)
 
       _ ->
-        return_sourcify_error(conn, "Unsuccessful sourcify verification", address_hash_string)
+        return_sourcify_error(conn, Sourcify.failed_verification_message(), address_hash_string)
     end
   end
 

apps/block_scout_web/lib/block_scout_web/controllers/api/rpc/contract_controller.ex

@@ -241,10 +241,10 @@ defmodule BlockScoutWeb.API.RPC.ContractController do
             )
 
           {:error, :metadata} ->
-            render(conn, :error, error: "Sourcify did not return metadata")
+            render(conn, :error, error: Sourcify.no_metadata_message())
 
           _ ->
-            render(conn, :error, error: "Unsuccessful sourcify verification")
+            render(conn, :error, error: Sourcify.failed_verification_message())
         end
 
       {:error, %{"error" => error}} ->

apps/explorer/lib/explorer/third_party_integrations/sourcify.ex

@@ -7,6 +7,9 @@ defmodule Explorer.ThirdPartyIntegrations.Sourcify do
   alias HTTPoison.{Error, Response}
   alias Tesla.Multipart
 
+  @no_metadata_message "Sourcify did not return metadata"
+  @failed_verification_message "Unsuccessful Sourcify verification"
+
   def check_by_address(address_hash_string) do
     chain_id = config(:chain_id)
     params = [addresses: address_hash_string, chainIds: chain_id]
@@ -307,4 +310,8 @@ defmodule Explorer.ThirdPartyIntegrations.Sourcify do
     chain_id = config(:chain_id)
     "#{base_server_url()}" <> "/files/any/" <> chain_id
   end
+
+  def no_metadata_message, do: @no_metadata_message
+
+  def failed_verification_message, do: @failed_verification_message
 end