Running Safari with my WebKit build doesn't work well

I build WebKit fallowing the documentation. It seem to finish without problems. But when I run safari it doesn't work very well.

I have Safafi 13.1 and Catalina.

1) Get the code

git clone https://git.webkit.org/git/WebKit.git WebKit

I then did this because he documentation says but I'm not sure if it matters for this

cd WebKit
git svn init --prefix=origin/ -T trunk https://svn.webkit.org/repository/webkit
git config --replace svn-remote.svn.fetch trunk:refs/remotes/origin/master
git config --replace svn-remote.svn.rewriteRoot https://svn.webkit.org/repository/webkit
git svn fetch

2) Build

git checkout -b my_branch
Tools/Scripts/build-webkit --debug

3) Running Webkit

Tools/Scripts/run-safari --release

but got

Can't find built framework at "/.../WebKit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore".

I then did Tools/Scripts/run-safari --debug and open safari but doesn't work very well. If I put a website in the search bar it never loads. Google seems to open but all very slow.

In the console:

➜  WebKit git:(my_branch) Tools/Scripts/run-safari --debug
Starting SafariForWebKitDevelopment with DYLD_FRAMEWORK_PATH set to point to built WebKit in /.../WebKit/WebKitBuild/Debug.
2020-05-11 13:09:44.209 SafariForWebKitDevelopment[13199:124164] +[NSXPCSharedListener endpointForReply:withListenerName:]: an error occurred while attempting to obtain endpoint for listener 'SandboxBroker': Connection invalid

And then if I try to go to a specific website:

ERROR: InjectedBundle::decodeBundleParameters failed to decode bundle parameters: value for key 'NS.objects' was of unexpected class 'WBSSearchProvider'. Allowed classes are '{(
    NSNumber,
    NSSet,
    NSArray,
    NSString,
    NSTimeZone,
    NSData,
    NSDate,
    NSURL,
    NSDictionary,
    NSNull,
    NSUUID
)}'..
/.../WebKit/Source/WebKit/WebProcess/InjectedBundle/mac/InjectedBundleMac.mm(110) : bool WebKit::InjectedBundle::decodeBundleParameters(API::Data *)
2020-05-11 13:10:32.888 SafariForWebKitDevelopment[13199:124693] Creating client/daemon connection: BA6BBD25-BF13-474A-A3BC-92E0A3269E09
2020-05-11 13:10:32.939 SafariForWebKitDevelopment[13199:124693] Got the query meta data reply for: com.apple.MobileAsset.CoreSuggestions, response: 5
2020-05-11 13:10:32.939 SafariForWebKitDevelopment[13199:124693] rawData is null skipping
2020-05-11 13:10:32.940 SafariForWebKitDevelopment[13199:124693] Got the query meta data reply for: com.apple.MobileAsset.CoreSuggestions, response: 5
2020-05-11 13:10:32.940 SafariForWebKitDevelopment[13199:124693] rawData is null skipping

How can I make it work properly so I can start developing and testing a patch for WebKit?