Act_runner fails to fetch task (interface conversion)

Hello everybody.

act_runner fails to fetch task with the following generic error:

time="2024-07-25T13:47:32+02:00" level=error msg="failed to fetch task" error="unknown: 500 Internal Server Error"

The log at Gitea side is:

2024/07/25 13:47:33 ...eb/routing/logger.go:78:func1() [W] router: failed    POST /api/actions/runner.v1.RunnerService/FetchTask for [ip-address-redacted]:0, panic in 43.4ms @ <autogenerated>:1(http.Handler.ServeHTTP-fm), err=interface conversion: interface {} is string, not map[string]interface {}
2024/07/25 13:47:33 ...rs/common/errpage.go:26:RenderPanicErrorPage() [E] PANIC: interface conversion: interface {} is string, not map[string]interface {}
/usr/local/go/src/runtime/panic.go:770 (0x441131)
/go/src/code.gitea.io/gitea/modules/web/routing/logger_manager.go:116 (0x1ceffc8)
/usr/local/go/src/runtime/panic.go:770 (0x441131)
/usr/local/go/src/runtime/iface.go:262 (0x412c24)
/go/pkg/mod/gitea.com/gitea/act@v0.259.1/pkg/model/workflow.go:418 (0x14f6146)
/go/pkg/mod/gitea.com/gitea/act@v0.259.1/pkg/jobparser/jobparser.go:104 (0x15145f6)
/go/pkg/mod/gitea.com/gitea/act@v0.259.1/pkg/jobparser/jobparser.go:45 (0x151365a)
/go/src/code.gitea.io/gitea/models/actions/task.go:281 (0x15e17b1)
/go/src/code.gitea.io/gitea/routers/api/actions/runner/utils.go:26 (0x23dc1ee)
/go/src/code.gitea.io/gitea/routers/api/actions/runner/runner.go:159 (0x23daff5)
/go/pkg/mod/connectrpc.com/connect@v1.15.0/handler.go:52 (0x23d59ce)
/go/src/code.gitea.io/gitea/routers/api/actions/runner/interceptor.go:59 (0x23da0c2)
/go/pkg/mod/connectrpc.com/connect@v1.15.0/handler.go:84 (0x23d5445)
/go/pkg/mod/connectrpc.com/connect@v1.15.0/handler.go:265 (0x23b42ee)
/go/pkg/mod/code.gitea.io/actions-proto-go@v0.4.0/runner/v1/runnerv1connect/services.connect.go:207 (0x23d38b5)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/usr/local/go/src/net/http/server.go:2214 (0x23e01c1)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/usr/local/go/src/reflect/value.go:596 (0x4fef25)
/usr/local/go/src/reflect/value.go:380 (0x4fe038)
/go/src/code.gitea.io/gitea/modules/web/handler.go:172 (0x1cf9bdc)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/pkg/mod/github.com/go-chi/chi/v5@v5.0.12/chain.go:31 (0x1cf0a25)
/go/pkg/mod/github.com/go-chi/chi/v5@v5.0.12/mux.go:459 (0x1cf39c5)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/pkg/mod/github.com/go-chi/chi/v5@v5.0.12/mux.go:73 (0x1cf15ce)
/go/pkg/mod/github.com/go-chi/chi/v5@v5.0.12/mux.go:327 (0x1cf2f5a)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/pkg/mod/github.com/go-chi/chi/v5@v5.0.12/mux.go:459 (0x1cf39c5)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/src/code.gitea.io/gitea/modules/web/routing/logger_manager.go:122 (0x1cefe6a)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/src/code.gitea.io/gitea/modules/web/handler.go:136 (0x1cfa079)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/pkg/mod/github.com/chi-middleware/proxy@v1.1.1/middleware.go:37 (0x25511f3)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/src/code.gitea.io/gitea/modules/web/handler.go:136 (0x1cfa079)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/src/code.gitea.io/gitea/routers/common/middleware.go:49 (0x255256f)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/src/code.gitea.io/gitea/modules/web/handler.go:136 (0x1cfa079)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/src/code.gitea.io/gitea/routers/common/middleware.go:40 (0x25520fb)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/src/code.gitea.io/gitea/modules/web/handler.go:136 (0x1cfa079)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/src/code.gitea.io/gitea/routers/common/middleware.go:103 (0x2551555)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/src/code.gitea.io/gitea/modules/web/handler.go:136 (0x1cfa079)
/usr/local/go/src/net/http/server.go:2171 (0x9ed348)
/go/pkg/mod/github.com/go-chi/chi/v5@v5.0.12/mux.go:90 (0x1cf158d)
/go/src/code.gitea.io/gitea/modules/web/route.go:163 (0x1cfb487)
/usr/local/go/src/net/http/server.go:3142 (0x9f0a4d)
/usr/local/go/src/net/http/server.go:2044 (0x9ebd27)
/usr/local/go/src/runtime/asm_amd64.s:1695 (0x47ccc0)

Can you help me solve this?