Error: no generic function found for ‘crossprod’
Call sequence:
13: stop(gettextf("no generic function found for %s", sQuote(f)), 
        domain = NA)
12: getGeneric(f, TRUE, envir, package)
11: methods:::.mergeMethodsTable2(impMethods, newtable = expenv[[metaname]], 
        expenv, metaname)
10: .mergeImportMethods(impenv, ns, impvars[[i]])
9: namespaceImportFrom(self, asNamespace(ns), from = from, except = except)
8: namespaceImport(ns, loadNamespace(i, c(lib.loc, .libPaths()), 
       versionCheck = vI[[i]]), from = package)
7: loadNamespace(j <- i[[1L]], c(lib.loc, .libPaths()), versionCheck = vI[[j]])
6: asNamespace(ns)
5: namespaceImportFrom(ns, loadNamespace(j <- i[[1L]], c(lib.loc, 
       .libPaths()), versionCheck = vI[[j]]), i[[2L]], from = package)
4: loadNamespace(j <- i[[1L]], c(lib.loc, .libPaths()), versionCheck = vI[[j]])
3: asNamespace(ns)
2: namespaceImportFrom(ns, loadNamespace(j <- i[[1L]], c(lib.loc, 
       .libPaths()), versionCheck = vI[[j]]), i[[2L]], fr
Execution halted
Error in getGeneric(f, TRUE, envir, package) : 
  no generic function found for ‘crossprod’
Calls: <Anonymous>
Execution halted

Error: no generic function found for ‘crossprod’
Call sequence:
13: stop(gettextf("no generic function found for %s", sQuote(f)), 
        domain = NA)
12: getGeneric(f, TRUE, envir, package)
11: methods:::.mergeMethodsTable2(impMethods, newtable = expenv[[metaname]], 
        expenv, metaname)
10: .mergeImportMethods(impenv, ns, impvars[[i]])
9: namespaceImportFrom(self, asNamespace(ns), from = from, except = except)
8: namespaceImport(ns, loadNamespace(i, c(lib.loc, .libPaths()), 
       versionCheck = vI[[i]]), from = package)
7: loadNamespace(j <- i[[1L]], c(lib.loc, .libPaths()), versionCheck = vI[[j]])
6: asNamespace(ns)
5: namespaceImportFrom(ns, loadNamespace(j <- i[[1L]], c(lib.loc, 
       .libPaths()), versionCheck = vI[[j]]), i[[2L]], from = package)
4: loadNamespace(j <- i[[1L]], c(lib.loc, .libPaths()), versionCheck = vI[[j]])
3: asNamespace(ns)
2: namespaceImportFrom(ns, loadNamespace(j <- i[[1L]], c(lib.loc, 
       .libPaths()), versionCheck = vI[[j]]), i[[2L]], fr
Execution halted