Add redirection on unavailable video due to follow constraints

shared/models/server/index.ts

@@ -7,4 +7,5 @@ export * from './emailer.model'
 export * from './job.model'
 export * from './log-level.type'
 export * from './server-config.model'
+export * from './server-error-code.enum'
 export * from './server-stats.model'

shared/models/server/server-error-code.enum.ts

@@ -0,0 +1,3 @@
+export const enum ServerErrorCode {
+  DOES_NOT_RESPECT_FOLLOW_CONSTRAINTS = 1
+}